Idaho water quality
Idaho has 1,972 active public water systems (4,398 on file total), 773 of them graded by TapGraded.
Grade distribution
Biggest water systems
VEOLIA WATER IDAHO
BOISE, ID · 264,978 served
MERIDIAN WATER DEPT
MERIDIAN, ID · 147,340 served
NAMPA CITY OF
NAMPA, ID · 100,200 served
CALDWELL CITY OF
CALDWELL, ID · 74,000 served
IDAHO FALLS CITY OF
IDAHO FALLS, ID · 69,450 served
POCATELLO CITY OF
POCATELLO, ID · 58,231 served
TWIN FALLS CITY OF
TWIN FALLS, ID · 56,121 served
COEUR D ALENE CITY OF
COEUR D ALENE, ID · 54,115 served
REXBURG CITY OF
REXBURG, ID · 40,695 served
KUNA CITY OF
KUNA, ID · 32,038 served
Lowest-graded systems
Active, graded systems serving at least 10,000 people, ordered by lowest Tap Grade first.
BURLEY WATER DEPT
BURLEY, ID · 10,345 served
MOUNTAIN HOME, CITY OF
MOUNTAIN HOME, ID · 14,651 served
BLACKFOOT CITY OF
BLACKFOOT, ID · 13,224 served
GARDEN CITY WATER AND SEWER SYSTEM
GARDEN CITY, ID · 12,500 served
MERIDIAN WATER DEPT
MERIDIAN, ID · 147,340 served
POCATELLO CITY OF
POCATELLO, ID · 58,231 served
FALLS WATER COMPANY INC
IDAHO FALLS, ID · 22,650 served
TWIN FALLS CITY OF
TWIN FALLS, ID · 56,121 served
REXBURG CITY OF
REXBURG, ID · 40,695 served
MOSCOW WATER DEPT
MOSCOW, ID · 26,000 served
Cities in Idaho
Source: EPA SDWIS/ECHO · Data as of 2026Q2